@okie,
Alright. I'll try again to give some basic information.
Opposite to the the situation in e.g. the USA, Germany had a distinctive party system, even in times of the empire: from the left to the right.
When the empire collapsed, the party structures that have evolved over decades stayed as they were but now became responsible for the every day politics.
Slightly changes in party names happened, but from 1918/19 onwards they were generally spoken
- the conservatives (mainly represented by the 'Deutschnationale Volkspartei' ["German National People's Party"] on the right side,
- the political Catholicism (respresented by the 'Zentrum' ["Centre"] and the 'Bayerische Volkspartei' ["Bavarian People's Party"] in the centre of the political spectrum,
- the right ('Deutsche Volkspartei' ["German People's Party"]) and left ('Deutsche Demokratische Partei' ["German Democratic Party"]) liberal parties,
- and the Social-Democrats on the left side.
On the extreme left wing were the Communists. On the extreme right later the NSDAP.
About 20 more splinter parties tried to get a seat in the 'Reichstag' (and even more on in the various states). Some succeeded, like the "Independent Social-Democrats", the "Evangelical German People's Party" and a few more.
As generally know, it was a big chaos in Germany. (Until 1920, still more than 400,000 men were fighting in the various [about 300] 'Freicorps' [free corps, unofficial military organisations].)
All poltical parties had been surprised by the "revolution" (= end of the monarchy and sudden start of democracy).
While the "established" parties tried to re-define their former party programs to a democratic, republican attitude, new parties had to try to find supporters.
The 'Deutsche Arbeiter Partei' (DAP) started in Munich, with the idea of promoting their extremist right-wing views under a left name.
The idea would have worked elsewhere perhaps better but in Munich: Munich/Bavaria had enough parties - and was the very first left/communist/socialist republic in Germany (though only for a short period, but what I mean is that the left side was already "taken").
Hitler and his 'group' not only changed the name, but their program was a lot better focused on what they thought Germans wanted: everything from the right to the left for every social stratum, centred around their racial ideas (what the DAP already had had before, too).
(The Communists didn't want such qua dogma, but focused on Marxism and the USSR.)